The focus here is on ethylene-insensitive, root-specific mutants that affect root growth. Mutants are isolated in the following way. 1-aminocyclopropane-1-carboxylic acid (ACC) a precursor of ethylene, at 5 X 10exp-7 M inhibits wildtype root growth by decreasing root cell length. Mutants not showing this reduction have been isolated. Among these mutants, those affecting plant response to ethylene are discarded. So far, one mutant, leir10 has been studied in some detail. There are five objectives: 1) determine phenotype of leir10/ere and leir10/mre double mutants. Mutants in these classes have impaired root growth under standard conditions. Inhibition of ethylene synthesis relieves the mutant phenotype. These epistatic studies get at the question of whether leir10 is involved in ethylene synthesis or perception. 2.) Measure, via RT-PCR transcript levels of cloned genes involved in ethylene synthesis or perception in wildtype and leir10. 3.) Screen for second-site suppressors and enhancers of leir10 4.) Continue preliminary studies of other putative ethylene-insensitive, root-specific mutants. 5.) Screen additional T-DNA populations for additional ethylene-insensitive, root-specific mutants